Telephone-transmitter



(Nomodel.) L 'f A. STROMBBRG an A. CARLSON.

Y TBLBPHDNBTRANSMITTER. 110.567.324. n Y lPmntjed-sept-,1896.

` UNITED PATEIxIfr @Elric-,

`ALFRED`sirrtoMesasAND ANnIaovcARLsoN, or cI-IIcAGo, ILLINOIS.

IELEPHONEJRANSMITTER.

` SPECIFICATION forming part of Letters Patent No.`56 77,324,ldated September 8, 1896.

' Application filed October 2Q, y1895.; serial lfl'o. 567,237. (No model.)V y

.To a/ZZ whom if may' concern: Be it known that we, ALFREDSTROMBERG and ANDRov CARLSON, citizens of the United States, residing at Chicago, in the county 'of Cook and Stateof Illinois, have invented a certain new and useful Improvement inT'elephone-Transmitters, (Case. No. 22,) of which; the followi-ngis afull, clear, concise, and eX- act description, reference being had tothe accompanying drawings, forming a part of this specification. Our inventionV relates totelephone-transmitters, and more particularly to improvements in the transmitter described in Letters PatentNo. 545,922, granted to us September 10,1895.V Y

The objectof our invention is to provide means for protecting the diaphragm against the evil eifects of the moisture from the breath of one speaking into the transmitter, and, furthermore, to provide improved means for supporting` the carbon electrodes or disks in position. In transmitters in which the diaphragm is formed of metal oxidation frequently takes place, due to the moisture from the breath of the person speaking into the transmitter, the diaphragm becoming oxidized or rusted to such a degree as to materiallyimpair the operation of the transmitter. The diaphragm is sometimes made of carbon, being formed of a thin carbon plate, which serves as one electrode of the transmitter. The moisture from the breath is equally destructive of the carbon diaphragm, as 4the moisture penetrates the carbon and causes it to disintegrate. Furthermore, the presence of the moisture very materially impairs the operation of the transmitter.

lVit-h these objections in view it is the object of the present invention to provide means forpreventing the access of moisture tothe outer surface of the diaphragm, and for this purpose we provide an additional or auxiliary diaphragm situated in front of the main diaphragm, and made of a moisture-proof material, such as hard rubber, isinglass, or the like. The auxiliary diaphragm or plate may be mounted upon the surface of the Lmain diaphragm, or, preferably, situated at a short distance from the main diaphragm, so that an air-space is formed between the two diaphragms. In the transmitter of our invencushion is absent.

. bles or wastes away.

tion thisairfs'pace performs auseful function,

as it forms'a sort of cushion, which prevents the 'transmitter from being-too sensitive and permits the approach of the speaker nearer to the diaphragm than is advisable when the Ve are thus enabled to construct a telephone which is absolutely moisture-proof, as it is impossible for moistu re to gain access to the interior of the transmitter,the auxiliary diaphragm being secured at the edge, so that the ent-rance of the moisture is prevented, the construction of the casing being otherwise such that the moisture cannot enter at other points.

provision of improved means for mounting the carbon disks, which serve as the electrodes, in their supports. Vhen a carbon disk-is to be mounted upon a metallic diaphragm, it has been the practice heretofore to electrolytically deposit copper upon the face of the carbon disk, whereby the disk may be soldered to the metallic diaphragm, or to such other metallic support as may be provided. We have found, however, that the acid to which the carbon is subjected when in the electrolytic bath has a deleterious effect upon the carbon, impairing the efliciency of the transmitter, while the carbon soon crum- `It is thus desirable to secure kthe carbon disk toits support in some other manner than by the deposition of copi per thereon, and, in accordance with our invention, we mount the carbon disk in a cuplike or cylindrical support, the rim of the cup A further feature of our invention is the I y or .cylinder being turned in to engage the oarbon disk at the edges, and thus maintain the carbon in position.

XVe will describe our invention by reference to the accompanying drawings, in which- Figure 1 is a sectional view of the transmitter embodying our invention. Fig. 2 is a view of the diaphragm, showing the carbon disk mounted thereon through the agency of the cup or cap of our invention.` Fig. `3 is af sectional view of the disk and cup before the rim is turned in. Fig. 4t is a similar view after the rim is turned in. Fig. 5 is a View,

partially in section, showing the stationarilymounted disk before the rim is turned in. Fig. 6 is a view thereof after the rim has been turned in. Fig. 7 is aview showing the auxiliary diaphragmV mounted directly upon the face of the main diaphragm.

Like letters refer to like parts in the several figures.

The casing as preferably constructed comprises two parts a a', adapted to be bolted or otherwise secured together, a hard-rubber mouthpiece l) being screwed into the portion a. vAn insulating-plug c passes through the rear of the casing, and through this plug the screw d passes, a look-nut CZ being provided for maintaining the screw in any adjusted position. The stationary carbon electrode or disk e is mounted upon the end of the screw d. Within the casing is provided th'e main diaphragm f, and in close proximity thereto the auxiliary diaphragm f', the diaphragms being held in position preferably by springs f2 f2, which press the edges of the diaphragm against the upper face of the casing. The diaphragm f is made of metal or carbon, and the diaphragm f is made of rubber, mica, or the like. Upon the diaphragm f is mounted the carbon electrode e', between which and the electrode e is interposed granulated carbon. A ring g of felt is secured to the diap'hragml and presses by its face against the electrode e or its support toV prevent the escape of the granulated, carbon, while not materially affecting the movement of the diaphragm. The carbon disk or electrode c is maintained within the cap or cup e2, having a rim adapted to be turned in at the edge, as shown in Fig. 4, to clamp the electrode in position. The electrode is thus held in int-imate contact with the surface of the metallic 'cup or cap, and the cup may be soldered or otherwise secured to the diaphragm. The carbon remains in its original pure state and is 'not affected as is the case when the carbon is electroplated. Likewise, a cup or cap e2 is provided upon the end of the screw CZ, within which the electrode e is placed, the end of the rim being turned in to clamp the electrode in position and to press the electrode rmly against the metallic cap to secure good eleotrical contact.

Having described our invention, what we claim as new, and desire to secure by Letters Patent, isy.

l. In a telephone-transmitter the combination with the main diaphragm, of the auxilf iary diaphragm situated infront of the main'g diaphragm and composed of material which` is not affected by moisture, the edges of saicL auxiliary diaphragm beingirmly clamped t prevent the entrance ofmoisture or Watei around the edges of the diaphragm, an air; space being left between said diaphragmsl whereby the transmitter is rendered moistureii i proof and the transmission is facilitated by the air-space; substantially as described. y

2. Inatelephone-transmitter, the combina tion with a metal diaphragm, of a metal our l soldered or otherwise secured to the rear face of said diaphragm, said cup being providec x with a shallow peripheral rim, a thin plate o] disk of carbon forming one electrode of thc transmitter and resting within said cup, th

ledges of the rim of the cup being turned ir to rest upon the outer face of the thin carbor disk to maintain the same securely within `the cup without crushing -the edges of th(l thin carbon disk, a plate or disk of carbonl` l mounted stationarily and situated opposite i the face of the thin carbon disk mounted upon' the diaphragm, granulated carbon interposed ALFRED STROMBERG. ANDROV CARLSON.

Titnessesz W. OLYDE JONES, i JOHN W. SINCLAIR. 

